Rigid recording disk cartridges having a circular, floppy magnetic or optical disk rotatably mounted within the disk cartridge case are well known. The cartridge is mountable on a disk drive apparatus to rotate the recording disk within the cartridge and access the disk by a magnetic or optical recording head for recording or reproducing information. The disk cartridge includes a rotatable magnetic or optical disk and a rectangular cartridge case for housing the disk having a central axis. A head access opening is formed in the cartridge to permit a recording head to access the magnetic disk. The head access opening is opened and closed by the shutter which slides along a front peripheral edge between open and closed positions.
A pair of annular wipers are disposed in the cartridge to remove debris from the disk surface. The wipers are made of cleaning material, and cover the entire recording surface area of the disk. One wiper is disposed between each side of the disk and the respective upper and lower shells. The wipers are biased into contact with the disk surfaces to clean the disk.
In U.S. Pat. No. 4,626,949 to Brock, et al., a disk cartridge having cleaning wipers mounted on radial projections is disclosed. However, the projections are formed on both shells of the cartridge to cause the disk to undulate in and out of the projections.
U.S. Pat. No. 4,677,517 to Gelardi et al. discloses a cleaning apparatus for disk cartridges in which the lifter or wiper is metallic and is disposed in a ramp molded into the cartridge shell. Opposing rib configurations are not disclosed.
In one commercially known embodiment of cleaning apparatus shown in FIG. 1 and described in U.S. Pat. No. 4,620,247 to Papciak et al. and German Patent No. DE 3,540,560, a biasing device, such as a cantilevered lifter 58, is mounted on the lower shell 14 for biasing the wipers 54, 56 into contact with the disk 18. A series of parallel ribs 59 is mounted on the upper shell 12 opposite the biasing lifter 58. The ribs 59 are generally parallel to the direction of rotation of the disk 18 and generally perpendicular to the radius of the disk 18, being oriented approximately 15.degree. relative to the head access slot. The width of the ribs 59 ranges from 0.38 mm (0.015 in) to 0.76 mm (0.030 in), and the pitch of the ribs 59 ranges from 1.78 mm (0.070 in) to 2.03 mm (0.080 in).
However, this configuration does not insure consistent cleaning along the entire radius (from the inner diameter to the outer diameter) of the disk. Most of the cleaning of the disk by the wipers occurs along the leading edge of the ribs due to the force of the cantilevered lifter. The rib surface area along this leading edge next to the disk is only approximately 25% to 40% of the recording surface of the disk. Additionally, the voids between the ribs prevent sufficient pressure from being applied to the disk because the liner is pressed into and conforms to the voids. This leaves gaps where the wiper does not contact the disk.
Although replacing the ribs with a second lifter eliminates the voids, it does not establish a consistent axial disk location. The difference between the height of the disk against the lifters (the axial distance from the reference plane, defined as the bottom of the lower shell, to the lifters) and the height of the disk between the drive heads (the axial distance from the reference plane to the drive heads) varies unacceptably. When two lifters are used, this axial or vertical height difference, or angle of attack, depends on the relative force of the top lifter to the bottom lifter. This relative force depends on the relative bend angles of the lifters, their horizontal placement within the cartridge, and their relative thicknesses. As the relative production tolerances for the lifter are significantly larger than for injection molded ribs, the axial location of the disk varies more with two lifters than with the lifter and rib system. Additionally, using two lifters increases material costs and cartridge assembly time.
Although replacing the ribs with a second lifter, as is known in the prior art, eliminates the voids, it does not establish a consistent difference between the height of the disk against the lifters and the height of the disk between the drive heads. When two lifters are used, the vertical height difference, or angle of attack, depends on the relative force of the top lifter to the bottom lifter. This relative force depends on the relative bend angles of the lifters, their horizontal placement within the cartridge, and their relative thicknesses. As the relative production tolerances for the lifter are significantly larger than for injection molded ribs, the height location of the disk varies more with two lifters than with the lifter and rib system. Additionally, using two lifters increases material costs and cartridge assembly time.